Anzac Day has been commemorated in Harefield yearly on the 25th of April every year since 1921. It commemorates the soldiers of the Australian and New Zealand Army Corps(ANZAC) who served in the Gallipoli Campaign. After World War 2, Anzac Day was broadened to include all members of the armed forces of Australia and New Zealand severing in all conflicts and peacekeeping operations.

The Churchyard in St Mary’s has a war cemetery that holds the graves of 112 ANZACs who were treated in Harefield on the site of the current Harefield Hospital. The war cemetery is maintained by the Commonwealth War Graves Commission (CWGC).

Anzac Day, 25th April, has become a most significant annual event in the Harefield village calendar